A5 Magnetic Bed Mod

Zrvl

This is my first post so I want to thank everyone that contributes to this site.  I haven't had to ask any questions yet because all of the information I needed to get my A5 printing well is available here.  Thanks to all who contribute.

I decided to attempt this mod based on a YouTube video by Improper Engineering:

https://www.youtube.com/watch?v=-HI0PLQ3ThU&t=870s

I like the bed supplied with the A5 but there have been a few times where I had to chisel away at a large print to get it to release from the surface.  

So, I purchased a 12-3/8" x 24" piece of 0.02" spring steel from McMaster-Carr:

https://www.mcmaster.com/#9072k13/=1e2wi5h

And a box of longer bed screws because I knew I needed to raise the bed to allow for clearance of the temporary bed clips and the future install of the magnets:

https://www.mcmaster.com/#92125a151/=1e2wj3x

I cut the spring steel in half and attached a sheet of Gizmo Dorks PEI, I wanted to test it before adding the magnets so I clipped it with spring steel paper clips to the hot bed:



I really liked how this worked out, the bed heats up very fast and removing parts is as easy as unclipping the steel sheet and flexing it, the parts literally drop off.

The spring steel was expensive and probably not necessary.  The PEI sheet adds enough rigidity to the assembly that it would take a lot of effort to bend a plain sheet of 26ga. galvanized steel with the PEI attached, save about $30 and get the galvanized from Home Depot if you decide to attempt this mod.

Now it was time to install the magnets to make removal of the sheet assembly easier.

I purchased high temp N42SH Neodymium magnets from Applied Magnets:

https://www.magnet4less.com/product_info.php?products_id=906

The N42SH magnets are good to 150 C so they should not suffer from loss of strength or thermal cycling like other magnets.

At first, I thought I'd saturate the bed to give a strong bond between the print sheet and the bed.  I also had left over strips of the 3M 468MP adhesive that were supplied with the sheet of PEI so I used them to attach the magnets to the underside of the hot bed.



That was a mistake.  I tested the strength of the magnets holding the build sheet to the bed and it was very strong.  The problem came when I placed the bed on the printer carriage.  Even with the longer screws and double spring guides for spacers, the entire bed immediately collapsed the springs and stuck to the top cover of the printer.  These magnets are EXTREMELY strong!  They even overwhelmed the adhesive and pulled the magnets from the hot bed, sticking to the top of the printer cover.

So I tried another approach where I reduced the number of magnets:



 Although this helped, the center magnet caused a noticeable bow in the center of the hot bed and the magnetic attraction of the printer cover began pulling the magnets loose from the hot bed.

I bench tested using only 4 magnets at the corners and this appears to hold the build sheet adequately.  My next step is to find a stronger adhesive and continue testing.

I'll continue to update this discussion with my progress.

Samuel Pinches

Thanks for sharing! This looks like a nice upgrade, especially if you want to work with PETG or other materials that can be hard to remove. I use PEI on my Z-603S already, it's a great printing surface.

How much did the magnets cost including shipping?

Zrvl

The magnets were $1.49 each plus shipping.  Overall cost with shipping was about $2.15 each.

The N42SH magnets are hard to find and the shipping costs were high from everyone.

lsh60

Hola a todos.
Os dejo este video creo que os va ayudar mucho en este tema.

Espero que sea de vuestro interes.
Saludos.
Luis.

Samuel Pinches

I actually received one of these for review - I will let you know the results once I have tested them

Magnetic Flexible Printing Bed @ Banggood

Zrvl

Keep us posted, I'm curious to see what effect the continuous temperature cycling of the flexible magnet will have on its strength.

I have had success modifying the magnet mounts with an ABS printed holder mounted below the bed in each corner.  I'll post an update when I get some time.  They have been working well for about a month now.

Samuel Pinches

I like your solution more, but I’m curious if this cheap option is any good.

Andre

You can get a 305 by 305 mm² spring steel for 23€ incl. shipping at AliExpress:
 https://s.click.aliexpress.com/e/ct3kjKBm

That seems quite cheap.

But the steel cover the A5 uses is a problem with magnets downside the bed Some ideas:

1. Glue the magnets with high temperature silicone.

2a. Make the heatbed at least 2cm higher. You loose build volume. Needs some ingeneering to make stable spacers. Or

2b. Replace the steel base housing of the JGAurora by aluminium...

2c. Buy samarium-cobald magnets, 5mm diameter, 2.5mm thickness (0.73€/Pcs). Drill 2.5mm deep piches in the heatbed, carefull not to damage the heater. Glue the magnets inside the pitches. If you damage them heater, use a silicone heater and forget about the original pcb-traces.

I thought about such modifikation myself, but as long as there are no 305by305 PEI Powder Coated Spring Sheets (textured like the Prusa mk3 one), I see no urgend need.

Flexible magnetic shields: They so not like temperatures above 80°C. So PLA ist O.K., but even PET-G ist critical.Also the surface so not like contact with the nozzles - it melts. So make shure bed leveling ist O.K. before every print

Samuel Pinches

I agree, a spring steel bed is probably best. I am also looking forward to the PEI sheets becoming available from prusa. I did end up receving my magnetic bed sticker system and it works really well for PLA and PETG. Not sure how long the magnet coating would last for ABS, but I did one print and it seemed to be still sticking fine.

CHEAP 3D Printer Magnetic Bed Platform Upgrade - Review

Andre

PEI Sheets are available from Prusa (29€). They are two PEI-Sheets glued on spring steel. PEI powder coated are the ones hard to get.

The only way to get the powder coated Sheet (beside ordering a complete mk3) is the MK2.5 Update (150€, incl. Bondtech gears, 12v magnetic heatbed, pinda probe, nuctua fan, filament sensor, 250g PET-G black and 100g harribo).

I ordered my mk3 with PEI-sheet, because it wasn't available powder coated. To get the powder coated sheet afterwards I ordered the MK2.5 upgrade - using all the other upgrade parts for other printers.

Powder coated is the best. Nothing compares to it...

But there is an small manufacturer in Canada, selling PEI powder coated sheets. I got one on eBay (about 60€). It works well, but has finer structure. I prefer Prusa-struture for optical reasons, but the canadian structure for technical parts which need very flat side.

Maybe the canadian manufacturer will make bigger sheets If there is enough interest?

Edit: He does already! eBay Articlenumber 332812730227. It is for the CR10, but should fit on the JGAurora A5 also. Its 305x305mm².

Darius R. Steele

Thanks for posting this, I love it.  So I am in the middle of this mod now.... I made the PEI and steel flex plate... my question is how did you remove your glass bed from the heater?  Did you have to break it?  I am also adding an inductive probe.... took forever to figure that out.